With the development of society, more and more people begin to use large-size liquid crystal displays (LCDs). As shown in FIG. 1, it is a backlight module 100 nowadays, wherein numeral 110 is a light emitting diode (LED) light source, and numeral 120 is a light guide plate. The alignment between the LED light source 110 and the light guide plate 120 is achieved by a formed projection 131 on a plastic frame 130, which abuts against and positions the light guide plate 120. However, with the size enlargement trend of the light guide plate 120 and the progress of the thin-type design thereof, the pressure of the plastic frame 130 abutting against the light guide plate 120 by the formed projection 131 is already unable to ensure the complete alignment between the LED light source 110 and a light input side surface of the light guide plate 120, namely, the light input side surface of the light guide plate 120 and the light output surface of the LED light source 110 are matched with each other in the direction of Z axis. As a result, the light utilization rate of the light guide plate 120 is decreased, and the design cost of the light guide plate 120 is increased.
As a result, it is necessary to provide a light-guide-plate positioning sheet and a corresponding backlight module to solve the problems existing in the conventional technologies.